ANALOG KEYS only: OSC1 makes a sound when triggered and set to GND / INL / IN R.
I found this behaviour on firmware 1.35, and and was hoping for a fix with the latest FW release. As I still can reproduce it with FW 1.40, I just wanted to document it somewhere and hope this is the right place.
Elektron’s support has confirmed the behaviour, it seems to be hardware related (“PCB crosstalk”) and is coming from the oscillator, not from the filters or overdrive. It might get fixed with a future firmware update, but there is no date yet. A4 mkI / mkII are not affected.
What’s happening?
If you want to route external audio through the AK’s filters (manual page 72) you need to trigger and open the AMP envelope of the track you want to route your audio through. This results in a rather weak but constant sound coming from OSC 1 of the used track. It seems that OSC 1 is not really off or grounded but gets triggered by the keyboard or the sequencer. And this signal somehow gets to the audio path, together with the external audio. This behaviour is identical for all four audio tracks, but only on OSC1, OSC 2 is not affected.
If you want to reproduce this:
- initialize a new project
- set all 8 OSCs to GND (or IN L or IN R)
- set all 8 OSC LEVs to 0 (or else, this setting has no effect on the behaviour)
- set all AMP VOLs to 127
- MASTER VOLUME to full
- play the keyboard: you will now hear the melody you play. The sound tracks the keyboard perfectly and is velocity sensitive. The effect can be heard better with higher notes.
Or just follow the manual page 72 without any external source connected.
My workaround for now:
OSC2 is not affected, so I route external (mono) audio through there. In addition, I set OSC1’s waveform to TRI with an OSC LEV = 0. At least for me, this works sufficiently. I believe the “softer” waveform makes it less noticeable.